Thermodes are devices used for local application of heat and pressure, typically in soldering applications known as ‘Hot-bar reflow soldering’. Once the thermode is brought into contact with a desired location, localized heating is produced by direct resistance heating of the tip of the thermode. The ‘soldering gun’ is a common example.
The main advantage of thermode soldering is the very rapid temperature change (up to 1000° Celsius per second) with precise control over the temperature while the component parts are being mechanically held by thermode contact pressure. Also, since the hottest portion of the thermode is typically in direct contact with the part bond area, efficient heat transfer occurs and rapid heating of the item is possible. The bond area is the area(s) of the part being processed where a reflow soldered bond is desired between at least two surfaces. Since the tips have little thermal mass, rapid cooling and solidification of the completed bond is possible. Forced air cooling can additionally be used to reduce the time required for the soldering cycle.
There are several styles of thermodes in common use, which differ mainly by the shape of the tip and material used. A thermode typically includes the following elements:                Terminals: electrical contacts where power is applied.        Mount: means of mechanically supporting the thermode (possibly the same structure as supports the terminals).        Shank: means of supporting the tip and conducting current to it.        Tip: high resistance section where the majority of heat is developed.        Transition zone: means of joining the tip to the shank.        Working surface: the portion of the tip, which comes in contact with the item to be heated.        Thermocouple: a device for determining the working temperature, attached to the tip near the working surface        
Issues may arise when the thermode, especially the thermode tip, requires cleaning due to a build-up of flux/solder residue and gradual metallurgical contamination of the working surface (collectively referred to as residue or debris). Even with the no-clean flux formulations, which may contain less than 5% solids, there is still residue build-up over time as the actual burn-off amount for no-clean fluxes is generally about 50% of the initial flux weight. Cleaning off the residue may require hours of downtime of the manufacturing system and reduced service life, which can cost a company many thousands of dollars of lost revenue over a year. Current methods may require the thermode soldering tips to be abrasively scrubbed or chemically cleaned every 150 to 175 soldering cycles.
Currently, various thermode tip cleaning methods are employed; although not without their disadvantages. Another common method for thermode tip cleaning is the use of a sponge soaked in water or a chemical cleaning solution. An air blast may also be used to clean the thermode tip. Both the air blast method and wet sponge method generally do not eliminate the need for mechanical scrubbing of the thermode, but may somewhat reduce the frequency of the mechanical scrubbing. Each of these methods typically requires additional tooling at the soldering site. Thus, there is a need for a method of cleaning a thermode that overcomes at least some of the deficiencies of conventional systems and methods.